Hemostatic sheath introducers are well known in the art as devices for facilitating insertion, removal and manipulation of stents, catheters or like devices into a vein or artery. A procedure has been developed called Transjugular Intrahepatic Portalsystemic Shunts (TIPS), in which a catheter is inserted into the jugular vein via a sheath introducer. A sheath introduced is an access device comprising a cannula with fluid barrier valve and an access port. The cannula portion is inserted into a patient's blood vessel, typically an artery, and a number of different devices are insertable into the sheath introducer and into the vessel with an objective being to cause minimal trauma to the vessel and surrounding area.
Intrahepatic portal-systemic shunts are artificial fistulas between branches of the portal vein and the systemic circulation in the substance of the liver. The insertion and deployment of such shunts are among the most complex procedures in interventional medicine. During the procedure a number of catheters or similar devices must be inserted into a blood vessel via the sheath introducer. Currently available sheath introducers, such as that described in U.S. Pat. No. 4,000,739, issued to Stevens, and its progeny, utilize a straight bodied sheath introducer and are normally used for insertion into certain areas of the body. Insertion of a cannula into the jugular vein involves a less flexible site because the curved jaw and neck area provide awkward placement of a sheath introducer relative to the patient's body.
The sheath introducer of Stevens utilizes a straight body and co-axially aligned cannula, with a tapering body portion integrating with the cannula. Because the cannula is mounted in the center of the bottom of the body, this sheath introducer design has a disadvantage that when it is inserted into the vessel the body of the introducer can lift the cannula away from the surface of skin area, possibly causing stress and trauma to the vessel underneath and kinking the introducer cannula. Additionally, the access port is co-axially aligned with the cannula requiring insertion of catheters to be made substantially horizontal to the skin and a catheter may be difficult to insert where the cannula is inserted near the uneven topography of the jaw and neck region. It would be desirable to have a cannula that would angle away from the skin to permit more facile insertion of a catheter and reduce pulling and trauma to the vessel during insertion. It would also be desirable to have a cannula that extended eccentrically from the body of the introducer to minimize bending of the cannula with respect to the vessel and to prevent or reduce the likelihood of kinking the cannula.